/*
 * Java CMPP API
 * Copyright (C) 1998 - 2002 by Xu Youming
 * 
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 * 
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 * 
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 * 
 * A copy of the LGPL can be viewed at http://www.gnu.org/copyleft/lesser.html
 * Java CMPP API author: xuym@bc-info.net
 * Java CMPP API Homepage: http://cmppapi.sourceforge.net/
 * $Id: MessageIdSequenceScheme.java,v 1.1 2008/03/19 02:56:56 xym Exp $
 */
package com.bci.cmpp.util;

/**
 * The default sequence numbering scheme. This implementation starts at sequence
 * number 1 and increments by 1 for each number requested, resulting in the
 * sequence numbers <code>1..2..3..4..5..6..7..8..n</code>. If the sequence
 * number reaches as far as <code>Integer.MAX_VALUE</code>, it will wrap back
 * around to 1.
 * 
 * @author Xu Youming
 * @version 1.0
 */
public class MessageIdSequenceScheme implements SequenceNumberScheme {

	private int num = 1;

	public MessageIdSequenceScheme() {
	}

	/**
	 * Construct a new DefaultSequenceScheme that starts the sequence from
	 * <code>start</code>.
	 */
	public MessageIdSequenceScheme(int start) {
		num = start;
	}

	public synchronized int nextNumber() {
		if (num == 65535) {
			num = 1;
			return (65535);
		} else {
			return (num++);
		}
	}

	public synchronized int getAndAdd(int nth) {
		if (num == 65535) {
			num = 1;
		}
		int ret = num++;
		num = num + nth - 1;
		num = num > 65535 ? (num - 65535) : num;
		return (ret);
	}

	public synchronized int peek() {
		return (num);
	}

	public synchronized int peek(int nth) {
		return (num + nth);
	}

	public synchronized void reset() {
		num = 1;
	}
}